(1) Field of the Invention
The present invention relates to an apparatus for recovering a specific ingredient in sea water, particularly to an apparatus for recovering lithium in sea water.
(2) Related Art Statement
There are various ingredients dissolved and present in sea water. Recovery and effective utilization of such various ingredients are particularly effective for cases where land resources are poor. Recently, investigations and developments of adsorbents have proceeded, and excellent adsorbents for recovering ingredients in sea water have been developed. As such adsorbents, adsorbents for adsorbing lithium, uranium, etc. are known, for example. Lithium is dissolved almost uniformly in sea water at a rate of about 170 ppb. Uranium is dissolved in sea water at a far lower rate of about 3 ppb.
According to an apparatus for recovering such a specific ingredient in sea water, an adsorbent is fixedly held in sea water, and that ingredient is adsorbed with the adsorbent in the state that ocean current is being spontaneously contacting the ocean current (JP-A 01-108324).
There is known a further improved adsorbing apparatus in which while sea water is taken in upwardly, a specific ingredient is adsorbed onto the adsorbent during the intake period. This apparatus can recover the specific ingredient in sea water with no problem when sea is calm and it is fine with a constant waterline surface.
However, according to such prior art methods, when the adsorbent is fixed in sea water, the flow rate of the ocean current relative to the adsorbent is not constant and usually very small. Thus, there are problems that since the adsorbent is in a stationary state, the adsorbing speed decreases, and the specific ingredient in sea water around the adsorbent only is adsorbed to make sea water thin in that ingredient and consequently lessen the adsorbed amount of the ingredient. Further, it is difficult to move the adsorbing apparatus to a safe place in case of bad weather such as typhoon.
Further, it is difficult to prevent backward flow of sea water which would occur when the waterline surface lowers and thus the water level in the adsorbing bed tank rises higher than the waterline surface in the case that the conventional adsorbing apparatus is being effecting the adsorbing operation in sea waving. There is a problem that if the sea water flows backwardly in the adsorbing bed tank, the adsorbent in the tank flows out along the backward flow direction of the sea water.
Further, once the adsorbent flows out, it flows into sea as it is. Consequently, it is impossible to recover the adsorbent. Therefore, an adsorbing apparatus has been desired, which can control the flow-out direction of the sea water and recover the adsorbent again in the adsorbing bed tank even if it flows out. However, such an adsorbing apparatus has not been known yet.
It is an object of the present invention to provide a recovering apparatus which can prevent the adsorbent from flowing out of the adsorbing bed tank and effectively recover a specific ingredient in sea water, while only as little power energy as possible is used.
In order to accomplish the above-mentioned object, the present inventor contrived an apparatus in which a precipitating section is provided between a sea water intake opening and a sea water intake pipe for precipitating an adsorbent and a specific ingredient in sea water is recovered through by circulating sea water in the tank.
An apparatus for recovering a specific ingredient in sea water, which comprises an adsorbing bed tank, a layer of an adsorbent charged on the bottom portion of the adsorbing bed tank, a sea water intake pipe provided in a bottom portion of the adsorbing bed tank, a sea water intake opening for taking in sea water and leading the sea water taken in to the sea water intake pipe, a communicating pipe communicating with an end of the sea water intake pipe, a precipitating section through which the communicating pipe communicates with the sea water intake opening, and an evacuator for discharging sea water inside the adsorbing bed tank, sea water inflow openings being provided between said sea water intake pipe and the tank and being provided with check valves, said check valve being adapted to only upwardly flow sea water into the adsorbent layer inside the adsorbing bed tank through the sea water inflow openings. In the above, a sectional area of the precipitating section as taken perpendicularly to a flowing direction of sea water is preferably larger than that of the sea water intake pipe.
According to the recovering apparatus of the present invention, since the sectional area of the precipitating section as taken perpendicularly to a flowing direction of sea water is larger than that of the sea water intake pipe, the adsorbent can be prevented from rising up to the sea water intake opening, even if sea water flows backwardly into the adsorbing bed tank and the adsorbent flows out into the sea water intake pipe. The adsorbent which is collected in the precipitating section having the larger sectional area can return to the adsorbing bed tank following the flow of sea water, when the apparatus is restored to its normal operational state.
In this way, the precipitating section functions to reduce the flow rate of sea water flowing out or change the flowing direction thereof to collect the adsorbent contained in the sea water flowing backwardly. The precipitating section may be designed in the form of a tank. If the flowing direction is changed, the precipitating section may be formed by designing a part of the communicating pipe as extending vertically.
In the present invention, the wording xe2x80x9csea water inflow openings being provided between said sea water intake pipe and the tank and being provided with check valvesxe2x80x9d includes variations, for example, the sea water inflow openings are provided at the peripheral wall of the sea water intake pipe, or the check valves may be considered to constitute a part of the sea water intake pipe or a part of the bottom of the adsorbent bed tank.
In the following, preferred embodiments of the present invention will be explained. Any combination of such preferred embodiments will be considered as preferred embodiments of the present invention, unless any adverse effect occurs.
As a preferred embodiment of the present invention, a sea water discharge opening is provided at a side portion of the adsorbing tank for discharging the sea water. The sea water overflowing the adsorbing bed tank can be discharged through this discharge opening. According to another preferred embodiment of the present invention, a vertically movable type overflow gate is provided in an upper portion of the adsorbing bed tank, and sea water is discharged through this overflow gate.
Such an overflow gate can set the water level inside the adsorbing bed tank. The permeating flow rate of the sea water flowing through the adsorbent layer is determined by a difference in water head which is obtained by subtracting the water level inside the adsorbing bed tank from the water level of the waterline. Therefore, the permeating flow rate of the sea water flowing the adsorbing layer can be changed by the overflow gate.
According to a further preferred embodiment of the present invention, a sea water-storing tank is provided upstream of the discharging opening for storing sea water flowing out through the overflow gate.
Such a sea water-storing tank can more finely change the permeating flow rate of the sea water flowing through the adsorbent layer. Further, when a water discharge pump is used as the evacuator, the presence of sea water in the sea water-storing tank can prevent a non-load running state of the water discharge pump without necessitating the control of the water discharge pump.
According to a still further preferred embodiment of the present invention, an ejector is provided at the bottom portion of the adsorbing bed tank for ejecting compressed air into the adsorbing bed tank.
Since the compressed air is ejected into the tank by the ejector, the compressed air can float the adsorbent and make uniform the permeating flow rate of the sea water flowing through the adsorbent layer.
The compressed air can float the adsorbent, so that the sea water present among the adsorbent particles can be collected near the sear the sea water ducking near pipe at the bottom portion of the adsorbing bedtank.
According to a still further preferred embodiment of the present invention, a suction/discharge unit is provided at the bottom portion of the adsorbing bed tank for sucking and discharging sea water.
This suction/discharge unit can remove the sea water stored in the bottom portion of the adsorbing bed tank to the outside. Particularly when the above ejector is used in combination, sea water among the adsorbent particles can be collected to near the suction/discharge unit for removal of the sea water, since the adsorbent can be floated with the compressed air ejected through the ejector.
As a still further preferred embodiment of the present invention, a lateral displacement-preventing unit is provided inside the adsorbing bed tank. The lateral displacement-preventing unit functions to prevent the lateral displacement of the sea water and the adsorbent inside the adsorbing bed tank in bad weather.
This lateral displacement-preventing unit is not particularly limited, so long as it can prevent the lateral displacement. For example, plural partition walls may be provided discontinuously inside the adsorbing bed tank, or a partition wall having plural holes may be continuously provided. This lateral displacement-preventing unit can prevent a great amount of the sea water and the adsorbent from rapidly horizontally move. Thereby, the recovering operation can be stably effected.
As a still further preferred embodiment of the present invention, the apparatus is adapted to recover lithium in sea water through adsorption with the adsorbent.
As a still further preferred embodiment of the present invention, a pouring unit is provided for pouring a desorbing liquid into the adsorbing layer. The specific ingredient in sea water adsorbed onto the adsorbent can be desorbed with the desorbing liquid poured by the pouring unit.
These and other objects, features and advantages of the invention will be well appreciated upon reading the following description of the invention when taken in conjunction with the attached drawings, with the understanding that some modifications, variations and changes could be easily made by the skilled person in the art to which the invention pertains.